1. Field of the Invention
The present invention relates to a 2D and 3D switchable display device and a liquid crystal lens thereof, and more particularly, to a 2D and 3D switchable display device and a liquid crystal lens thereof utilizing an electrode pattern design to achieve low capacitive loading.
2. Description of the Prior Art
The principle of three-dimensional (3D) stereoscopic display technique is to provide an observer separate images to his left eye and right eye respectively. The brain of the observer will then analyze and overlap the images perceived by his two eyes to generate gradation and depth in images, and furthermore, a sense of stereoscopic vision.
Currently, the stereoscopic display devices can mainly be categorized into two groups: time-sequential and spatial multiplexing. A time-sequential stereoscopic display device alternately provides the left eye of the observer with a left-eye image and the right eye of the observer with a right-eye image in sequence by scanning. The observer has to wear shutter glasses while watching the images. According to the display image at present, shutter glasses only allow a left-eye image sent to the left eye of the observer, but not the right eye of the observer, and vice versa in order to provide a 3D display. A spatial multiplexing stereoscopic display device primarily includes a parallax barrier stereoscopic display device. A parallax barrier stereoscopic display device can block the left eye and the right eye of the observer by disposing a parallax barrier in front of the display panel. Due to different observing angels, the left-eye images and the right-eye images can only be perceived by the left eye and the right eye of the observer respectively.
However, there are a lot of disadvantages in applications or effects of the conventional stereoscopic display device. First, the necessity of wearing shutter glasses while using the time-sequential stereoscopic display device causes inconvenience. Second, in the transitional process between the left-eye image and the right-eye image, part of the display images including both left-eye image and right-eye image have to be discarded in order to avoid perceptive confusion of the observer no matter the images are received by the left or the right eye. Therefore, brightness and frame rate will be decreased in the time-sequential stereoscopic display device and its display quality will be adversely affected. Moreover, a parallax barrier stereoscopic display device has a drawback of low brightness since part of the light will be blocked.
In light of the shortcomings, a liquid crystal lens type 3D display device has been developed. Referring to FIG. 1, FIG. 1 is a schematic diagram illustrating a conventional liquid crystal lens type 3D display device. As shown in FIG. 1, the conventional liquid crystal lens type 3D display device 10 includes a display panel 20 and a liquid crystal lens 30 disposed on the display panel 20. The liquid crystal lens 30 includes a first substrate 32, a second substrate 34, a plurality of first electrodes 36, a plurality of second electrodes 38, an insulating layer 40, a liquid crystal layer 42, and a third electrode 44. The first substrate 32 and the second substrate 34 are disposed opposite to each other. The first electrodes 36 are disposed on a side of the first substrate 32 facing the second substrate 34. The second electrodes 38 are disposed between the first substrate 32 and the second substrate 34. Each of the second electrodes 38 is corresponding to each of the first electrodes 36 and each of the second electrodes 38 is fully overlapped with each of the first electrodes 36, wherein each of the second electrodes 38 does not include any opening, gap, slot, hole, or slit. The insulating layer 40 is disposed between the first electrodes 36 and the second electrodes 38. The liquid crystal layer 42 is disposed between the second electrodes 38 and the second substrate 34. The third electrode 44 is disposed between the liquid crystal layer 42 and the second substrate 34. In a 3D display mode, the first electrodes 36 have a first voltage, the second electrodes 38 have a second voltage, and the third electrode 44 has a common voltage so that a lens effect will be generated when the liquid crystal layer 42 is driven by an electrical field. However, each of the second electrodes 38 is fully overlapped with each of the first electrodes 36, which causes capacitive loading between them. Thus, the liquid crystal lens 30 needs a higher voltage to be driven due to the capacitive loading, thus increasing the power consumption and driver chip cost. In addition, the lens effect will be adversely affected by the capacitive loading.